USS Monomoy (AG-40) was a commercial cargo ship acquired by the U.S. Navy during World War II. She was outfitted with guns and depth charges and sent into the dangerous waters of the North Atlantic Ocean to report on weather conditions and to act as escort vessel when required. She was manned by a U.S. Coast Guard crew and was eventually transferred to that agency as USCGC Monomoy (WAG-275).